Natasha Collins, 31, the fiancee of fellow TV presenter Mark Speight, who was born in Wolverhampton, was found with hot water burns covering about 60% of her body in the bath of the flat the couple shared in St John's Wood, north-west London, on January 3.

Westminster Coroner Dr Paul Knapman recorded a verdict of death by misadventure after noting that the presenter had a "very significant" amount of cocaine in her body at the time of death.

Distraught Speight called the emergency services after waking on the afternoon of January 3 to discover his fiancee dead in the bath, wearing a cropped top, Westminster Coroner's Court heard.

He told police the couple had been "partying" at home on their own and had taken cocaine and sleeping pills as well as drinking wine and vodka.

Speight was initially arrested on suspicion of murder and supplying Class A drugs, but last month Scotland Yard said he would not face any charges over the death.

Consultant pathologist Professor Sebastian Lucas told the inquest "high" levels of cocaine well within the range at which the drug can be fatal were found in Collins' blood stream.

Tests discovered 3.42 milligrams of a chemical resulting from the breakdown of cocaine per litre of blood. The coroner noted that deaths had occurred with levels of just 0.7 milligrams.

Alcohol was also found at less than the drink-drive limit, as were sleeping tablets at a "significantly high" level and small amounts of paracetamol.

There were burns over an estimated 60% of the presenter's body and face, including her tongue, which were consistent with being immersed in very hot water.

Collins also had a 0.4in (1cm) diameter hole in the septum of her nose - something Prof Lucas said was associated with cocaine use.

There were no bruises, fractures or other signs suggesting suspicious circumstances, but Collins' heart had contraction marks likely to have been caused by a stimulant drug such as cocaine.

The pathologist gave the cause of death as cocaine toxicity and immersion in hot water.

Police had the flat's boiler tested, but no defects were found.

Dr Knapman said the evidence pointed to the presenter collapsing in the bath.

He said: "It does seem from this that, whilst Mr Speight was asleep, at some stage she got up.

"She went into the bathroom. She had a bath.

"It is more likely than not that she had some heart problem when in the bath that caused her to lose consciousness and unfortunately she had the hot tap on."

The coroner noted that there would have been "sufficient" cocaine in the presenter's blood to kill her anyway.

He concluded: "We have heard that, within the privacy of their flat, they had embarked on adventurous behaviour, ignoring the risks.

"She has suffered the consequences by the ending of her life. It is a tragedy, of course, for all concerned."

Speight attended the court, looking drawn and gaunt, wearing blue jeans and a black jacket over a black T-shirt.

He was sworn in at the witness box but said he had nothing to add to the evidence that had already been heard.

After the verdict, he issued a joint statement with Collins' mother, Carmen, in which they paid tribute to the presenter.

The statement read: "Natasha was a loving daughter, fiancee, sister and friend, with a very positive attitude towards life.

"She was always thinking of others. We are devastated that her life was cut short and we miss her deeply. She will always remain in our hearts."

Speight, originally from Wolverhampton, is best known for the BBC children's art show SMart, which has run for more than 10 years.

In February he announced he was quitting the programme after his "tragic loss" left him unable to continue.

Speight shot to fame as the rubber-faced presenter of Children's ITV Saturday morning show Scratchy & Co. Collins starred alongside him on BBC children's show See It Saw It.